Sonic waves help recover natural gas from clogged storage sites

Could mean more gas for consumers during winter

The 10-pound sonic tool is intended to remove scale from gas storage wells.

Morgantown, WV - Natural gas companies
looking for better ways to unclog the wells they
use to withdraw gas from underground storage
reservoirs may soon be getting "good vibes"
from a low-cost sonic cleaning tool.

A Department of Energy-sponsored team of
companies led by Furness-Newburge Inc. of
Versailles, KY, has produced a prototype of a
system that uses sound waves to remove
inorganic matter and other debris that clog the
perforations of gas wells.

The technology has the potential to increase
significantly the efficiency at which natural gas is
withdrawn from storage reservoirs, making a
larger amount of gas available to consumers
during the winter heating season.

The prototype was developed through a
cooperative agreement between Furness-Newburge, Nicor
Technologies and TechSavants Inc., both of Naperville, IL, Baker Atlas,
Houston, TX, and the department's National Energy Technology
Laboratory.

Composed of an oscilloscope,
a power supply, a wire line reel
for the power cable, an
acoustical transducer, a
portable generator and
waterproof connections, the device is about two feet in length, two
inches in diameter, and weighs about 10 pounds.

The tool is lowered into a well where it emits relatively low-frequency,
high-intensity directed sound waves. After a relatively short time, the
sound waves force scale surrounding the well's opening to fall off.

"Who would have thought that the Navy acoustical training I received in
1966 would be used to clean out gas wells!" said Jim Furness,
principle investigator and partner at Furness-Newburge.

The basis for this device stems from a process that Furness helped
develop using acoustics to catalyze ozone and peroxide to prevent air
pollution in foundries.

The technology is not ultra-sound, Furness points out, "People can hear
the sound used for the process." The device is tunable within the range
of subsonic to 3kHz.

About two years of laboratory and bench-scale development yielded a
prototype that achieved impressive results during testing last year at
the Bashore No. 1 Observation Well, operated by Nicor Gas near
Pontiac, IL. More extensive field tests need to be performed along with
additional laboratory work before the tool can be used commercially,
but results so far have been encouraging.

On average, more than 17,000 gas storage wells lose 5 percent of
their ability to inject and withdraw gas from underground storage fields
each year. A Department of Energy-Gas Research Institute study found
that inorganic precipitate or scale was a leading cause of the problem.
Inorganic matter such as calcium carbonate coats a well's openings
from which gas is withdrawn. Over time, production can decline to the
point where over half of the field's deliverability can be lost. The gas
industry spends between $60 million and $100 million a year trying to
correct this problem.

Water analyses were conducted during the field tests demonstrated the
device's effectiveness in removing key constituents found in storage
well deposits. Water samples collected after the sonication tool was
used were compared with samples taken two months earlier. The
water chemistry indicated a significant increase in mineral salts as well
as increased levels of suspended matter - signs that the sonic cleaning
device was doing its job.

The amount of calcium, magnesium, iron, and bicarbonate in solution
increased by 100 percent, 60 percent, 60 percent, and 5,300 percent,
respectively, after sonication. The amount of suspended solids also
increased by 230 percent after sonication.

The acoustic portion of the tool is expected to sell for less than $15,000
and is compatible with standard wire-line equipment used routinely in
day-to-day field operations.

The second phase of the research will begin this summer. Along with
improving the tool so that it can operate with more rugged field
handling, more field testing will be done in different types of gas
storage reservoirs. Also, more definitive testing, such as gas-pressure
changes, will be performed to better quantify the system's
performance.

The Department of Energy's Office of Science is the single largest supporter of basic research in the physical sciences in the United States and is working to address some of the most pressing challenges of our time.